1. Field of the Invention
The present invention relates to a phosphoric ester (hereinafter referred to as phosphate for simplicity), a process for preparing the same and use thereof. More particularly, the invention relates to a non-halide phosphate having a phosphorinane structure and a hydroxyl group, a process for preparing the same and a flame-retarder and a flame-retarded resin composition containing the same.
2.Description of Related Art
Thermoplastic resins such as polypropylene, polystyrene or acrylonitrile-butadiene-styrene (ABS) resin and thermosetting resins such as polyurethane or phenolic resin have excellent characteristics of being able to be produced at relatively low costs, to be easily formed or the like. Accordingly, these resins are widely used for general daily goods including electronic parts and automobile parts. However, these thermoplastic resins and thermosetting resins (hereinafter referred to as resins) fire readily, and therefore, they easily burn or burn out once they catch fire. Especially a fire at public facilities such as electric facilities and communication cables may cause great damage to functions of a community.
For this reason, flame retardancy is required by laws in some fields such as electric appliances, automobile interiors, and textile fabrics for which such resins are used. Such flame retardancy regulations are known as the UL standard for electric appliances and as MVSS-302 for automobile-related products in the United States, for example.
For providing flame retardancy to a resin, a flame-retarder is generally added in preparation for resin products. Used as flame-retarders are inorganic compounds, organic phosphorus compounds, organic halogen compounds, organic phosphorus compounds containing halogens and the like.
Among the above-mentioned compounds, halogen compounds such as organic halogen compounds and organic phosphorus compounds containing halogens exhibit an excellent flame-retardant effect. These compounds, may however, generate a hydrogen halide by pyrolysis when resin products are molded. Hydrogen halides cause problems such as corrosion of metal molds, deterioration and coloration of resin itself. Furthermore, since hydrogen halides are toxic, they not only change work environment for the worse but also generate toxic gases such as hydrogen halide and dioxins, when burning, for example, in a fire, so that it produces ill effects on humans.
Inorganic compounds such as magnesium hydroxide and aluminum hydroxide are known as flame-retarders that do not contain halogens. However, these flame-retarders have only significantly poor flame-retardant effect. They need to be added to resins in great amount in order to exhibit sufficient effect, and as a result, deteriorate the properties of the resin itself.
For the above reasons, organic phosphorus compounds are generally used as flame-retarders exhibiting relatively good flame-retardant effect but not containing halogens. Typical examples of organic phosphorus compounds include aromatic phosphorus compounds such as triphenyl phosphate (TPP), tricresyl phosphate (TCP) and cresyldiphenyl phosphate (CDP). These are used as flame-retarders for a variety of engineering plastics such as phenol resin, epoxy resin and polyurethane.
These organic phosphorus compounds, especially TPP, have a low content of phosphorus, to which their flame retardancy is attributed, and therefore, are usually used as a mixture with halogen compounds to provide satisfactory flame-retardancy for resins. In the case where TPP is used alone, TPP must be added to resins in large amount and therefore may deteriorate the properties of the resins itself.
Japanese Unexamined Patent Publication No. SHO 55(1980)-110175 discloses the following compound as an additive providing flame retardancy to resins: ##STR3##
Japanese Unexamined Patent Publication No. HEI 6(1994)-321974 discloses the following compound as an additive providing flame retardancy to resins: ##STR4##
The above-mentioned compounds (IV) and (V), however, are solid. Therefore, it is difficult to add these compounds to resins, especially polyurethane foam, in a desired amount at a molding process. These compounds, when used, are pre-dispersed in polyol which is a raw material for resin in some cases. However, the dispersion of the compounds is not satisfactory because of their sedimentation. Furthermore, these compounds must be added to polyurethane foam in large amount to provide sufficient flame retardancy thereto, and therefore, significantly deteriorate the properties of this resin.
Japanese Unexamined Patent Publication No. SHO 58(1983)-117272 discloses a flameproofing agent composed of poly(oxyorganophosphate/phosphonate). This compound has a high phosphorus content (P%) and is excellent in flame retardancy, but does not have sufficient performance in either thermal resistance or resistance to hydrolysis. Further, the compound have some drawbacks, for example, in that it affects the natural properties of resins adversely and that it brings difficulty to the molding process.
Japanese Unexamined Patent Publication No. SHO 57(1982)-125259 discloses the following compound (39) as a stabilizer which provides weathering resistance and thermal stability to halogen-containing resins, though this compound is not a flame-retarder. This publication does not discuss flame-retarders for the resins. ##STR5##